Photo-Identification

Photo Identification Catalogues

Photo-identification (or photo ID) is a non-invasive technique used by scientists around the world to study whale and dolphin populations. The basis of photo ID is that each animal within a population is unique and has certain physical characteristics and distinctive markings which distinguish it from other individuals. Nicks or marks on the body surface are captured on camera during an encounter and then kept as a permanent record of the individual. The part of the animal used for photo ID varies between species but is most commonly the dorsal fin or tail fluke.

Once individuals have been photographed and identified, they can be added to the photo identification catalogue. As well as excellent photo quality, one of the most important aspects of photo ID research is that the catalogue is regularly updated with new images. In this way, changes to known individuals can be monitored over time, and hopefully new individuals can be added to the growing catalogue. Using this technique, researchers can monitor the movements of whales and dolphins, learn about their social structure and estimate the number of animals in a population.

HWDT has been using photo ID to study the whales and dolphins off the west coast of Scotland for many years and has established catalogues for the area’s minke whales, killer whales and bottlenose dolphins.

You can help

We are interested in obtaining images of whales and dolphins which might be suitable for photo-identification. Anybody with a reasonable SLR camera and lens can contribute to our better understanding of whales and dolphins in the Hebrides, by forwarding their images to sightings@hwdt.org

Useful Photo ID tips

Taking pictures of cetaceans for photo-identification is a challenging but worthwhile task. Here are some useful tips:

1) Focus mainly on capturing the dorsal fin (and tail fluke for humpback whales) 2) The dorsal fin should be parallel to the photographer at a 90° angle 3) Try to photograph both the left and right sides of the dorsal fin 4) For groups of animals, try to photograph as many individuals in the group as possible 5) Note down the date, time, location and group size of your encounter

Photo-Identification Catalogues

Minke whale photo ID catalogue

HWDT has been studying minke whales using photo ID, since 1990. Since then 98 individuals have been identified. Through this research, we have learnt that minke whales return to the same feeding grounds year after year. Some animals may remain in the area all summer being sighted multiple times over the course of a field season. This phenomenon of individual whales returning repeatedly to the same areas has been well documented in the Hebrides and is termed ‘site fidelity’. Site-fidelity makes sense for a large predator looking for, patchy resources such as fish shoals. The whales get to know an area, and increase their chances of finding food by repeatedly searching areas where they have previously found food.

The results of this research provide valuable foundations for future studies and could help to determine the wider distribution of these whales. By collaborating with other research groups across Europe and sharing photo ID catalogues, we may even be able to map the migration routes of certain individuals and find out where minke whales go in the winter.

Most of the photographs for this study have been collected by Sea Life Surveys, a local whale-watching business, and HWDT staff during research trips onboard Silurian. However anyone can contribute to this research by taking a photograph of your minke whale encounter and sending it to sightings@hwdt.org

HWDT has been studying bottlenose dolphins in the Hebrides since 2001. Over the years, our database of images has grown, but the rate of discovery of new individuals has been slow. It is likely therefore that the bottlenose dolphins can be considered resident to the area. If this is indeed the case, the Hebrides would be the third area to be identified in the UK with resident bottlenose dolphins, the other areas being Cardigan Bay (Wales) and the Moray Firth on the east coast of Scotland.

So far, it appears that there are two distinct groups of bottlenose dolphins in the Hebrides; an Inner Hebridean group of between 30 and 40 individuals ranging from Skye to Kintyre, and a smaller group of between 12 and 15 dolphins in the Barra Sound, Outer Hebrides. It is thought that these two groups do not associate with each other. This is in spite of the relatively small distances between the areas these dolphins occupy.

Most of photographs for this study have been collected by HWDT staff during research trips onboard Silurian. However anyone can contribute to this research by taking a photograph of your bottlenose dolphin encounter and sending it to sightings@hwdt.org

HWDT has been studying killer whales in the Hebrides using photo ID, since 1992. So far, 10 individuals have been identified in the Hebrides and there have been no matches yet with other individuals from catalogues in Iceland, Norway, Shetland and Orkney, suggesting that this group of killer whales may be resident in the Hebrides. However, one member of the Hebridean group, John Coe, has been photographed off the north coast of Ireland and more recently off the Pembrokeshire coast, Wales. This is the furthest south any of the Hebridean killer whales have been recorded

Most of photographs for this study have been collected by Sea Life Surveys, a local whale-watching business and HWDT staff during research trips onboard Silurian. However anyone can contribute to this research by taking a photograph of your killer whale encounter and sending it to sightings@hwdt.org